Science > Physics > thermal efficiency of commercial absorption freezer?
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Science > Physics |
| User: |
"" |
| Date: |
05 Oct 2006 04:05:03 AM |
| Object: |
thermal efficiency of commercial absorption freezer? |
Can we estimate the overall thermal efficiency of a Sibir kerosene
freezer?
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| User: "Shawn Hirn" |
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| Title: Re: thermal efficiency of commercial absorption freezer? |
05 Oct 2006 06:38:25 AM |
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In article <1160039103.428819.178800@i42g2000cwa.googlegroups.com>,
wrote:
Can we estimate the overall thermal efficiency of a Sibir kerosene
freezer?
What does the manufacturer say?
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| User: "AJH" |
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| Title: Re: thermal efficiency of commercial absorption freezer? |
06 Oct 2006 04:24:53 AM |
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On 5 Oct 2006 02:05:03 -0700, wrote:
Can we estimate the overall thermal efficiency of a Sibir kerosene
freezer?
I think Eric is about right, I looked at the refrigerant system for a
trawler a few years back, it used the waste engine heat and IIRC the
COP was about 0.7. See also this snippet from
<http://geoheat.oit.edu/pdf/tp51.pdf>
"For single-stage units, these temperatures
are : 12 psi steam (or equivalent hot water) entering
the generator, 85oF cooling water, and 44oF leaving chilled
water (ASHRAE, 1983). Under these conditions, a coefficient
of performance (COP) of approximately 0.65 to 0.70
could be expected (ASHRAE, 1983)."
So on a small scale unit I'd expect much lower performance.
AJH
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| User: "Roger Thorpe" |
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| Title: Re: thermal efficiency of commercial absorption freezer? |
10 Oct 2006 07:51:31 AM |
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If you're comparing it with vapour compression then you will need to
consider the thermal efficiency of electricity generation. I just
thought that it's worth mentioning, since to do otherwise prejudices
thermally driven machines.
--
Roger Thorpe
My email address is spamtrapped. You can work it out!
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| User: "Eric Sears" |
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| Title: Re: thermal efficiency of commercial absorption freezer? |
06 Oct 2006 03:49:58 AM |
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On 5 Oct 2006 02:05:03 -0700, wrote:
Can we estimate the overall thermal efficiency of a Sibir kerosene
freezer?
In my experience, absorption fridges and freezers generally use about
3 times the energy of a similar sized compressor fridge or freezer.
For example, a standard (not "low usage") fridge of 80 litres uses
about 600 watt-hr per day. A similar size of gas/12v/230v absorption
fridge (I have one) uses 1800 watt-hr a day under similar conditions.
So the likely answer is "not very efficient" - but I can't give any
other numbers.
Eric Sears
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